The influence of lymphocytes on the modulation of macrophage functions in altered immune states induced by Cryptococcus neoformans infection in rats has been investigated. In this report we observed a decrease of 'in vitro' phagocytic activity by peritoneal cells (PC) from rats that received T suppressor cells induced by cryptococcal infection, against both the same microorganism that stimulated this suppressor population (p < 0.05) and another non-pathogenic primary yeast (Candida tropicalis), (p < 0.02). The microbicide function of the PC from these animals present a significant decrease in challenge by C. tropicalis (p < 0.002) when compared with PC from animals transferred with T normal cells. The transference ofT suppressor cells induced by cryptococcal infection in animals immunized with human serum albumin-complete Freund's adjuvant (HSA-CFA) produces a significant alteration of the phagocytosis to HSA-human red cells (HSA-HRC) when compared with the phagocytosis observed in animals that received T normal cells or the phagocytosis of normal animals (p < 0.001). We could also observe that the DTH to H SA studied during 30 days was negative in rats transferred with PC sensitizated with HSA and treated with suppressor T cells, when compared with the DTH response of animals transferred with PC-HSA cocultured with normal cells (p < 0.05 21st day). The data presented in this paper illustrated that following infection of rats with C. neoformans there is a change in some population of accessory cells behavior reflected by the modification of several functions, such as phagocytosis, lytic activity and antigen presentation. * This group was considered as control. ** Peptone-elicited PC from normal animals (n > 5). *** P < 0.001 between groups. NA: non adherent.